1. Technical Field of the Invention
The present invention relates to a technology for analyzing features of sound.
2. Description of the Related Art
A technology for analyzing features (for example, tone) of music has been suggested in the art. For example, Jouni Paulus and Anssi Klapuri, “Measuring the Similarity of Rhythmic Patterns”, Proc. ISMIR 2002, p. 150-156 describes a technology in which the time sequence of the feature amount of each of unit periods (frames) having a predetermined time length, into which an audio signal is divided, is compared between different pieces of music. The feature amount of each unit period includes, for example, Mel-Frequency Cepstral Coefficients (MFCCs) indicating tonal features of an audio signal. A DP matching (Dynamic Time Warping (DTW)) technology, which specifies corresponding locations on the time axis (i.e., corresponding time-axis locations) in pieces of music, is employed to compare the feature amounts of the pieces of music.
However, since respective feature amounts of unit periods over the entire period of an audio signal are required to represent the overall features of the audio signal, the technology of Jouni Paulus and Anssi Klapuri, “Measuring the Similarity of Rhythmic Patterns”, Proc. ISMIR 2002, p. 150-156 has a problem in that the amount of data representing feature amounts is large, especially in the case where the time length of the audio signal is long. In addition, since a feature amount extracted in each unit period is set regardless of the time length or tempo of music, an audio signal extension/contraction process such as the above-mentioned DP matching should be performed to compare the features of pieces of music, causing high processing load.